According to this article the ideal running mantra is "One that's short, positive, instructive, and full of action words." They also recommend having several different mantras ready.
I used several during my half marathon last fall that I set a 4 minute PR at.
In the beginning I was all about "Run your own race" This was to prevent me from going out too fast and trying to keep up with all the people who did start out too fast. I also used "I will be seeing you later" at the beginning. and a lot of those people I did see later when I passed them.
The last 10k is started using some different ones including "Enjoy being fast" and "This is what you are here for, this is what you trained for. You are ready for this. You are trained for this" Okay the second one isn't very short, but it is very motivational for me. My pace for the last four miles was 7:11 verses the 7:25ish I ran the first half of the race. I was really in "the zone" and felt so good mentally and physically.
There are some other really good mantras out there like
Chicago Runner Girls "Ride the edge"
and Mile Posts "Dream Big" and how can you not love Saucony's "Find your strong" campaign.
If you listen to Marathon Training Academy podcasts the you have heard "Release the kraken".
It is important to dig out these mantras when you get a stitch in your side, feel like puking etc so that instead of focusing on the pain and letting it drag you down, you distract yourself and push on. Mantras help divert the mind from its dark thought and transcend the pain.
Tips for making a good mantra.
Stay positive! Remember you want to divert your mind from the pain, not focus on it. "This is my day"
Use energetic words. "Go for it" "Run strong"
Keep it short. You don't want to be struggling to remember your mantra, it should flow easily.
Make it instructive. Tell yourself what to do. Remind yourself how you should be feeling. "Be relaxed" "Dream Big"
or you can use this chart to help make a chant to pull you through on your run.
Be strong, embrace power.
Stride fierce, be bold.
The biggest key to a running mantra is finding one that works for you. If it doesn't resonate with you it won't be as effective. I like to try new ones out when I am doing a hard workout. Sometimes even the distraction of thinking up new ones is enough to help pull me through the workout.
Tell me some of your favorite mantras.